Resend my activation email : Register : Log in 
BCF: Bike Chat Forums


Intermittent Spark problem

Reply to topic
Bike Chat Forums Index -> The Workshop Goto page Previous  1, 2
View previous topic : View next topic  
Author Message

Easy-X
Super Spammer



Joined: 08 Mar 2019
Karma :

PostPosted: 10:23 - 23 Jan 2020    Post subject: Reply with quote

So the outside spinny bit is rubbing against the inside wiring thingy?

Sounds like the engine's suffered from a massive knock in the past and now things don't line up anymore Thinking

Is it the Woodruff key that's sheared? That's not normal Wink
____________________
Husqvarna Vitpilen 401, Yamaha XSR700, Honda Rebel, Yamaha DT175, Suzuki SV650 (loan) Fazer 600, Keeway Superlight 125, 50cc turd scooter
 Back to top
View user's profile Send private message You must be logged in to rate posts

Nobby the Bastard
Harley Gaydar



Joined: 16 Aug 2013
Karma :

PostPosted: 11:48 - 23 Jan 2020    Post subject: Reply with quote

That's the woodruff key alright but it's done more than sheer, its fucked the rotor entirely. The rotor seems have been flapping either side of the woodruff key which is odd.

It'll need a new one of each. Get someone whose slightly mechanically inclined to fit them.
____________________
trevor saxe-coburg-gotha:"Remember this simple rule - scooters are for men who like to feel the breeze on their huge, flapping cunt lips."
Sprint ST 1050
 Back to top
View user's profile Send private message You must be logged in to rate posts

Teflon-Mike
tl;dr



Joined: 01 Jun 2010
Karma :

PostPosted: 11:51 - 23 Jan 2020    Post subject: Reply with quote

Jay2903 wrote:
Any ideas what’s causing it ?

first up the 1 photo means nothing to me. What am I supposed to be seeing?
Moving on, If the inside of the rotor is grinding on a winding on the stator... something isn't running concentric.
Is the stator located correctly? Is the crank bent? Is the main bearing the crank runs on fooked?
The list of possibilities isn't too big.. but the implications of many of them are probably none too palatable....
Has the motor been torn down recently?
____________________
My Webby'Tef's-tQ, loads of stuff about my bikes, my Land-Rovers, and the stuff I do with them!
Current Bikes:'Honda VF1000F' ;'CB750F2N' ;'CB125TD ( 6 3 of em!)'; 'Montesa Cota 248'. Learner FAQ's:= 'U want to Ride a Motorbike! Where Do U start?'
 Back to top
View user's profile Send private message Visit poster's website You must be logged in to rate posts

Jay2903
Scooby Slapper



Joined: 03 May 2016
Karma :

PostPosted: 12:46 - 23 Jan 2020    Post subject: Reply with quote

Teflon-Mike wrote:

first up the 1 photo means nothing to me. What am I supposed to be seeing?
Moving on, If the inside of the rotor is grinding on a winding on the stator... something isn't running concentric.
Is the stator located correctly? Is the crank bent? Is the main bearing the crank runs on fooked?
The list of possibilities isn't too big.. but the implications of many of them are probably none too palatable....

I don’t think I’m explaining this very well. As far as I can tell everything’s concentric, the crankshaft is fine and the outside of the rotor hasn’t touched the stator windings at all. What appears to be happening is the inside of the rotor, the area that is scratched up in the image is pushing up against the field coil and the two are grinding together.
 Back to top
View user's profile Send private message You must be logged in to rate posts

Jay2903
Scooby Slapper



Joined: 03 May 2016
Karma :

PostPosted: 12:53 - 23 Jan 2020    Post subject: Reply with quote

No sure you can see this properly but I don’t think the two blue areas are touching. I think the red area on the rotor is touching the face of the field coil.

I suppose the two possibilities are, the rotor was sitting too far out or the field coil sits too far in.
 Back to top
View user's profile Send private message You must be logged in to rate posts

Tankie
Crazy Courier



Joined: 24 Feb 2017
Karma :

PostPosted: 18:11 - 23 Jan 2020    Post subject: Reply with quote

Jay2903 wrote:
Teflon-Mike wrote:
The Montesa motors, especially the Cota trials versions with a heavier mag-rotor for slow-running were notorious for sheared keys; I've lost about half a dozen over the years. When 'new' it was usually caused by the rotor not being so carefuly fitted. When old/Resto'd, it was a similar looseness, usually caused by a little surface rust on the rotor and or crank taper, and or looser worn rotor nut.

On resto, the advice was to use a little valve lapping past on the crank-shaft, and spend indeterminate hours working the rotor back and forth on the crank taper to a) get the surfaces properly clean of any surface rust and or crud' b) clean thoroughly with thinners (esp after lapping with valve past) c) To critically fit the rotor onto the crank, which meant using a copper mallet to actually get the rotor to interference fit to the crank taper, rather than merely relying on the pressure made by the, probably worn, rotor nut.

If that's any ideas for you.


Cheers, I’ve been looking at it and I can see the problem.
The inside of the rotor is rubbing against the field coil as you’ll probably be able to see in the image of the rotor. Any ideas what’s causing it ?

(I can’t upload the image of the field coil because the file is too large but that also has scratches like the ones on the rotor)


Check for float and runout on the end of the crank, if all is fine try to reposition the windings
____________________
Always learning, everyday is a school day
 Back to top
View user's profile Send private message Send e-mail You must be logged in to rate posts

mentalboy
World Chat Champion



Joined: 05 May 2012
Karma :

PostPosted: 23:49 - 23 Jan 2020    Post subject: Reply with quote

Jay2903 wrote:
mentalboy wrote:
How's this for a larf, you tell us what machine we're guessing about here and somebody familiar with that model might have some ideas.

If it's a trials then I haven't the foggiest - I know it's definitely not an old Thumper as they didn't have a leccy start and it can't be a mkIII Commando with the nasty Polish starter that never worked.


I think I mentioned earlier, it’s an xs500


Nope, not on this thread. It helps if you mention it at the start of a new thread whenever you post in the workshop.
Had a few of the smaller version, engines were reliable but the electrics were a bag of shite, especially the points, assume the same goes for the 500 or you wouldn't be here!!

What's the drive end of the starter motor look like? I'll wager it's stripped the dog. The fact that the motor is spinning but wouldn't turn over the engine and the rotor/stator grief, sorry to say, points to a bent crank.
____________________
Make mine a Corona.
 Back to top
View user's profile Send private message Send e-mail You must be logged in to rate posts

Teflon-Mike
tl;dr



Joined: 01 Jun 2010
Karma :

PostPosted: 01:05 - 24 Jan 2020    Post subject: Reply with quote

Almost 20 posts in, we get....
Jay2903 wrote:
2nd thing - what is the spec resistance for a xs500 plug cap.

And have to assume that he wants to know the resistance of an XS500 plug cap, 'cos the bike in question is an XS500....
Even though the question "What Bike?" was asked at least twice, and never answered in the twenty odd posts before... not really doing his best to help us help him, is he?
____________________
My Webby'Tef's-tQ, loads of stuff about my bikes, my Land-Rovers, and the stuff I do with them!
Current Bikes:'Honda VF1000F' ;'CB750F2N' ;'CB125TD ( 6 3 of em!)'; 'Montesa Cota 248'. Learner FAQ's:= 'U want to Ride a Motorbike! Where Do U start?'
 Back to top
View user's profile Send private message Visit poster's website You must be logged in to rate posts

jaffa90
World Chat Champion



Joined: 06 Apr 2016
Karma :

PostPosted: 01:23 - 24 Jan 2020    Post subject: Reply with quote

Teflon-Mike wrote:
Almost 20 posts in, we get....
Jay2903 wrote:
2nd thing - what is the spec resistance for a xs500 plug cap.

And have to assume that he wants to know the resistance of an XS500 plug cap, 'cos the bike in question is an XS500....
Even though the question "What Bike?" was asked at least twice, and never answered in the twenty odd posts before... not really doing his best to help us help him, is he?


Patience Teff, the o.p. had an iffy spark but now ok, also the plug cap i mentioned was ok but now not ok!
 Back to top
View user's profile Send private message You must be logged in to rate posts

wintelf94
Two Stroke Sniffer



Joined: 12 Nov 2019
Karma :

PostPosted: 17:51 - 26 Jan 2020    Post subject: Reply with quote

jaffa90 wrote:
Teflon-Mike wrote:
Almost 20 posts in, we get....
Jay2903 wrote:
2nd thing - what is the spec resistance for a xs500 plug cap.

And have to assume that he wants to know the resistance of an XS500 plug cap, 'cos the bike in question is an XS500....
Even though the question "What Bike?" was asked at least twice, and never answered in the twenty odd posts before... not really doing his best to help us help him, is he?


Patience Teff, the o.p. had an iffy spark but now ok, also the plug cap i mentioned was ok but now not ok!


Perhaps you may consider using a picture to help explain the problem further.
____________________
Beyond Limit
 Back to top
View user's profile Send private message You must be logged in to rate posts

Nobby the Bastard
Harley Gaydar



Joined: 16 Aug 2013
Karma :

PostPosted: 20:30 - 26 Jan 2020    Post subject: Reply with quote

Why the fuck are teffers and jaffa (firing blanks) 90 worrying about spark plugs when the fucking thing has chewed up the rotor that badly?
____________________
trevor saxe-coburg-gotha:"Remember this simple rule - scooters are for men who like to feel the breeze on their huge, flapping cunt lips."
Sprint ST 1050
 Back to top
View user's profile Send private message You must be logged in to rate posts
Old Thread Alert!

The last post was made 4 years, 62 days ago. Instead of replying here, would creating a new thread be more useful?
  Display posts from previous:   
This page may contain affiliate links, which means we may earn a small commission if a visitor clicks through and makes a purchase. By clicking on an affiliate link, you accept that third-party cookies will be set.

Post new topic   Reply to topic    Bike Chat Forums Index -> The Workshop All times are GMT + 1 Hour
Goto page Previous  1, 2
Page 2 of 2

 
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You cannot download files in this forum

Read the Terms of Use! - Powered by phpBB © phpBB Group
 

Debug Mode: ON - Server: birks (www) - Page Generation Time: 0.08 Sec - Server Load: 0.13 - MySQL Queries: 17 - Page Size: 78.36 Kb